Many cars carry a reserve canister in order to avoid running out of gas. At night in most areas all gas stations are closed. It is an offense to get stranded on a highway due to running out of gas. Some people take along a canister just to be on the safe side. These canisters are available in capacities of 5 liters and 10 liters. Five liters are sufficient for distances of between 50 and 100 km, depending on driving habits. This method has the following disadvantages:
1. The canisters have to be constructed in such a manner as to stand up to strict examinations. This is costly. PA0 2. Regarding the shape, one is limited to rectangular, flat shapes with rounded-off corners. PA0 3. Canisters which are not totally filled will, under hot temperatures, expand. They will last, but a ballooned-out plastic canister makes one feel uneasy. PA0 4. If such an expanded canister is opened, it makes a hissing, frightening sound. PA0 5. If thereby the canister is not held in such a position that the spout is up, gasoline is sucked out by the vacuum. PA0 6. In order to save the expense of a reserve canister many people are driving while carrying totally unsuitable laundry detergent containers or the like instead of canisters. PA0 7. But even approved canisters will in time release hydrocarbons through the walls. If a reserve canister is not checked from time to time, the tank will after some time no longer be full. PA0 8. A reserve canister should be secured since it otherwise might sometimes be thrown from one corner of the trunk to the other. PA0 9. Just when needed on vacation, the reserve canister is mostly buried lowest under the luggage. PA0 10. Where families have several cars, it is easily possible that the reserve canister is left behind. PA0 11. Since the reserve canister is not tied up, it is easily stolen. PA0 12. Reserve canisters having a capacity of 10 liters would be preferrable to those with 5 liters. But weak and/or clumsy persons might not be able to handle the 10-liter canisters. Therefore, 5-liter canisters are often preferred, despite the fact that according to the laws of physic (.sup.3 -law), 10-liter canisters are by far not twice as big as 5-liter canisters. PA0 13. The cap of the filling tube has to be unscrewed. In the exitement one quite often forgets to screw it back on. PA0 14. Each reserve canister needs a spout since the filling tube is always hidden so that it is impossible to fill straight from the canister, but quite often, these spouts have been lost. PA0 15. There is some skill and knowledge required to screw the spout onto the reserve canister, a skill which some people lack. PA0 16. Quite often good clothing is spoiled while the reserve canister has to be emptied. PA0 17. If the reserve canister has been emptied and if one then forgets to fill it up again the next time the tank is filled, one drives believing one has a full reserve canister. PA0 18. Sometimes the filling tubes have smooth walls. In that case all gasoline can run out and there is little smell of gasoline. But then the spout-has quite often the effect of a lever and the threaded part is strongly overworked. But then not all gasoline flows out of the spout, and after it has been used, the trunk if full of the smell of gasoline. Sometimes, however, the spout is bellowed. The threaded portion is in this case not overworked, but not all of the gasoline can flow out of the spout, and, after it has been used, the smell of gasoline remains all over the inside of the trunk. PA0 19. Due to the rectangular shape of the reserve canister, one can never make use of the less required hollow spaces in the trunk. Since the canisters have to be constructed in accordance with the requirements of DIN 16 904, intermediate sizes, such as for instance 41/2 liters or 7, 8 liters, are not possible. One is forced to manufacture either 5-liter canisters or 10-liter canisters. PA0 (a) a reserve tank permanently built into the car, said reserve tank being located within said piping system, said reserve tank having an upper wall and a wall with an opening therein, said reserve tank communicating with said filling tube, PA0 (b) a pipe protruding into said reserve tank, having at one end an upwardly open upper rim, whereby the height of said upper rim determines the volume of gasoline reserve inside said reserve tank, said pipe travelling via said opening through said wall of said reserve tank, said pipe forming at its other end the inlet to said main tank, PA0 (c) said ventilation box being located at a point above said upper wall of said reserve tank, PA0 (d) a by-pass hose which by-passes said opening, having an upper end which leads into a wall area of said reserve tank, and a lower end which leads to a point downstream of said opening, and PA0 (e) a valve provided on said by-pass hose, said valve having opening and closing means, which automatically re-adjust to a closed position.